Have you been told that your Northstar head bolts are stripped out and there is nothing that can be done to fix it because it had already been repaired once before? That's what happened to me! I bought a pre-owned 1996 Cadillac SLS and started having problems with it overheating, only to find out it had been repaired once before with Coil type and GM-approved Solid type inserts with synchronized internal and external threads. I was told that a new block would be around $7000.00! After doing some research, I found out that the Northstar engines were notorious for this problem.
I am a Tool and Die Maker by trade, and I developed the NS300L Insert System (Patent Pending) out of necessity and frustration. The NS300L Insert System is a thread repair kit I designed to outperform all other insert systems on the market designed for the Northstar engine. Unlike inserts with synchronized internal and external threads, the NS300L insert is a much larger and much stronger insert, with a much courser external thread.
The NS300L Insert System has over two times more thread engagement within the aluminum block than the GM-approved solid synchronized type inserts, and almost four times that of the common coil type inserts. There is nothing wrong with those other inserts, but the challenge is they do not always grip enough of the already weak aluminum, and have a tendency to pull out during the head bolt tightening process. Occasionally, those other types of inserts have failed only a few hundred miles after the repair. I have had several people contact me with this challenge, including Cadillac technicians.
My mechanic was impressed during his installation of my NS300L Insert System in my engine, especially with how easy they were to install.. Not long after that, word got around and I received a phone call from another garage in the area that had the same problem that I did, and heard that I had developed my own insert kit. They had a Northstar that was repaired once before with Coil type inserts, that had stripped out of the block. At their request I made an insert kit for them and they loved it!
The inserts are 1- ¾ inches long and have a M11 X 1.5 internal thread.
Inserts will work in "93" through "99" 4.0/4.6L NorthStar engines and 2000 through 2003 with different depths of lower and upper bank holes.
I received a quote for a solid insert kit with synchronized internal and external threads to do all 20 bolt holes for over $350.00 (the same inserts that pulled out of my block ), and a oversized insert kit to do all 20 holes for over $400.00.
Frequently Asked Questions.
Q - What makes the NS300L Insert System more reliable than the GM-approved insert?
A - The NS300L is a high quality high-strength insert, with a much courser external thread, having over two times more thread engagement within the aluminum block than the GM-approved insert.
Q - Why should I purchase the NS300L Insert System over other insert kits on the market?
A - Piece of mind! Several customers, including Cadillac mechanics, have commented that they were very impressed with the quality and strength of the NS300L insert, and wished they had purchased my kit in the first place rather than going through the expense and frustration of a second repair. These repairs generally cost between $2800 and $4500!
Q - Is the alignment block the only thing that keeps the drill straight? I noticed that the GM-approved kit has a bolted template, and it uses a drill bushing to guide the drill and tap.
A - No, it is not necessary to use the alignment block to guide the drill bit. The first thread in the head bolt hole starts about 1-1/4" below the deck surface. The unthreaded portion of the larger hole above the threads is approximately the same diameter as the drill provided in the kit, which works very well as a built-in drill bushing to keep the drill bit square to the original hole. The alignment block (also known as a "tap block") is used to start the tap square … a common machine shop practice for starting taps straight.
Q - I noticed that the GM-approved kit has a stop-collar on the drill bit. What keeps your drill bit from drilling too deep?
A - The reason the GM-approved kit uses a stop-collar and locating fixture, is because the depth of their hole revolves around their locking feature. They have a flange around the top of their insert to create a positive stop so that the installation tool (a tool much like a thread forming tap) also forms the last couple of threads on the bottom of the insert. The flange prevents the insert from turning during this process. This locking feature expands the last couple external threads of the insert, preventing the insert from turning out in the event that the head bolts would need to be removed later. This locking feature also creates a high amount of unnecessary outward pressure in an area of the engine block that is not very thick to begin with. My inserts are designed without the need for a flange, eliminating the need for a stop collar and eliminating unnecessary outward pressure. The drill bit in my kit is designed to stop when it reaches the bottom of the hole. This is accomplished by removing a portion of the drill point, preventing the drill bit from cutting deeper than the original hole. The drill bit’s cutting edges are also ground in a manner that helps prevent them from grabbing and twisting itself into the hole.
Q - Can the NS300L Insert System be used if the engine has previously been repaired with coil type or a GM-approved "first repair" kit?
A - Absolutely, and my inserts may be your only recourse, short of buying another engine block.
Q - Can I use the original head bolts with your kit?
A - You can, but GM recommends that you purchase new head bolts due to the old bolts being stretched.
Q - Will I be able to purchase only inserts in the future, or do I have to purchase the kit every time?
A - The inserts can be purchased individually.
Success of the NS300L insert kit is based on the inserts being installed correctly and square to the deck surface. It is recommended that the inserts be installed by a mechanic experienced in drilling and tapping holes. When installed correctly, coustomers have found that the NS300L insert system has exceded there expectations.
Insert Kit includes:
Installation instruction
21 Threaded inserts (steel).
1 Tap Drill (17/32" - same size as the counter bores in engine block).
1 5/8-11 Plug Tap
1 5/8-11 Bottom Hand Tap
1 Tap and Tap Drill Alignment Block.
1 "Tap Magic" tapping fluid.
1 LOCTITE 266,(shown) or Permatex high temp. high strength thread lock(10ml).
